RESUMO
OBJECTIVE：To establish the method for the con tent determination of related substances in belinstat. METHODS ： HPLC method was adopted and the principal component self-control comparison method with correction factor was used to calculate the contents of related substances. The determination was performed on ODS-AM column with 1.02％ potassium dihydrogen phosphate buffer （pH value adjusted to 3.5 with phosphoric acid ）-acetonitrile（85∶15，V/V）as mobile phase A ，1.02％ potassium dihydrogen phosphate buffer （pH value adjusted to 3.5 with phosphoric acid ）-acetonitrile（30 ∶ 70，V/V）as mobile phase B （gradient elution ），at the flow rate of 1.0 mL/min. The column temperature was set at 30 ℃，and the detection wavelength was 220 nm. The sample size was 10 μL. RESULTS：The linear ranges of belinstat and impurities A ，D，F，G，H were 0.113-1.693， 0.050-1.496，0.117-1.750，0.098-1.471，0.120-1.799，0.100-1.506 μ g/mL（r≥0.999 7）. The correction factors of the last 5 impurities were 1.0，1.0，1.2，1.5，1.0；the detection limits were 0.250，0.590，0.490，0.600，0.500 ng，respectively. The quantification limits were 0.500，1.170，0.980，1.200，1.000 ng，respectively. The recoveries were 90.18％-111.48％（RSD＝ 1.52％-4.78％，n＝9）. RSDs of stability （100 h）and precision tests were no more than 16％，and the durability was good. Impurities A ，D and H were detected in 3 batches of belinlestat ，the contents were 0.030％-0.038％，0.019％-0.022％ and 0.012％-0.013％，respectively. The contents of other maximum monomer impurities were 0.012％-0.013％ and the total impurities were 0.075％-0.084％. Impurities B ，C，F，G were not detected. CONCLUSIONS ：The method for the content determination of related substances in belinstat has been successfully established ，and the method is accurate and specific.
RESUMO
OBJECTIVE： To establish the method for simultaneous determination of four known related substances （olmesartan，olmesartan ester dimer ，olmesartan ester alkene ，benzothiadiazine impurity ，called impurity A ，B，C，D for short ）in Olmesartan medoxomil hydrochlorothiazide tablets. METHODS ：HPLC-principal component self-control with correction factor were adopted. The determination was performed on YMC-Triart C 8 column with mobile phase A consisted of acetonitrile- 0.015 mol/L potassium dihydrogen phosphate solution （pH adjusted to 2.8 with phosphoric acid ）（70 ∶ 30，V/V），mobile phase B consisted of acetonitrile-0.015 mol/L potassium dihydrogen phosphate solution （pH adjusted to 2.8 with phosphoric acid ）（15 ∶ 85，V/V）at the flow rate of 0.8 mL/min（gradient elution ）. The detection wavelength was set at 265 nm，and column temperature was 25 ℃. The temperature of injector was 4 ℃；the injection volume was 10 μL. RESULTS：The correction factors of impurity A ，B，C，D were 1.42，1.17，0.89，0.92，respectively. The linear range of olmesartan medoxomil ，hydrochlorothiazide and impurity A ，B，C，D were 0.252 7-7.580 0，1.152 1-4.562 9，0.244 0-18.299 0，0.244 7-3.670 8，0.265 2-3.978 3 and 0.149 9-4.497 3 μg/mL（r≥ 0.999 7），respectively. The limits of detection were 0.084 2，0.050 7，0.081 3，0.081 6，0.088 4，0.050 0 μg/mL，respectively. The quantitative limits were 0.252 7，0.152 1，0.244 0，0.244 7，0.265 2 and 0.149 9 μg/mL，respectively. The results of intermediate precision ，stability（24 h）and repeatability tests all met the relevant requirements. The average recovery rates were 104.00％-108.04％，102.00％-104.94％，100.99％-106.89％，92.00％-95.18％，102.00％-105.06％，103.90％-107.00％（n＝3）， respectively. The contents of impurity A ，B and D in 3 batches of Olmesartan medoxomil hydrochlorothiazide tablets were 0.90％ -1.00％ ，0-0.11％ ，0.16％ -0.24％ ，respectively. The impurity C and other impurities were not detected. There is no significant difference between the results measured by the established method and by the external standard method. CONCLUSIONS：The method has been proved to be highly sensitive and reproducible. It can be used to simultaneously determine four known substances in Olmesartan medoxomil hydrochlorothiazide tablets.